From 9955eacf96083e14d90897e5fbf5f68a8f97d307 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mike=20Schw=C3=B6rer?= <pubgit@mikescher.com>
Date: Sat, 23 Mar 2024 17:49:56 +0100
Subject: [PATCH] v0.0.419 JsonOpt

---
 dataext/optional.go | 67 +++++++++++++++++++++++++++++++++++++++++++++
 goextVersion.go     |  4 +--
 2 files changed, 69 insertions(+), 2 deletions(-)
 create mode 100644 dataext/optional.go

diff --git a/dataext/optional.go b/dataext/optional.go
new file mode 100644
index 0000000..b4667f7
--- /dev/null
+++ b/dataext/optional.go
@@ -0,0 +1,67 @@
+package dataext
+
+import (
+	"encoding/json"
+	"errors"
+)
+
+type JsonTwoWayMarshal interface {
+	json.Marshaler
+	json.Unmarshaler
+}
+
+type JsonOpt[T JsonTwoWayMarshal] struct {
+	isSet bool
+	value T
+}
+
+// MarshalJSON returns m as the JSON encoding of m.
+func (m JsonOpt[T]) MarshalJSON() ([]byte, error) {
+	if !m.isSet {
+		return []byte("null"), nil // actually this would be undefined - but undefined is not valid JSON
+	}
+
+	if m.value == nil {
+		return []byte("null"), nil
+	}
+
+	return m.MarshalJSON()
+}
+
+// UnmarshalJSON sets *m to a copy of data.
+func (m *JsonOpt[T]) UnmarshalJSON(data []byte) error {
+	if m == nil {
+		return errors.New("JsonOpt: UnmarshalJSON on nil pointer")
+	}
+
+	return m.value.UnmarshalJSON(data)
+}
+
+func (m JsonOpt[T]) IsSet() bool {
+	return m.isSet
+}
+
+func (m JsonOpt[T]) IsUnset() bool {
+	return !m.isSet
+}
+
+func (m JsonOpt[T]) Value() (T, bool) {
+	if !m.isSet {
+		return *new(T), false
+	}
+	return m.value, true
+}
+
+func (m JsonOpt[T]) ValueOrNil() *T {
+	if !m.isSet {
+		return nil
+	}
+	return &m.value
+}
+
+func (m JsonOpt[T]) MustValue() T {
+	if !m.isSet {
+		panic("value not set")
+	}
+	return m.value
+}
diff --git a/goextVersion.go b/goextVersion.go
index 70d8e5f..5df8ad4 100644
--- a/goextVersion.go
+++ b/goextVersion.go
@@ -1,5 +1,5 @@
 package goext
 
-const GoextVersion = "0.0.418"
+const GoextVersion = "0.0.419"
 
-const GoextVersionTimestamp = "2024-03-20T09:42:06+0100"
+const GoextVersionTimestamp = "2024-03-23T17:49:56+0100"